Medical probe device and method

ABSTRACT

A medical probe device for treatment of the prostate of a human male having a bladder with a base with a urethra formed by a urethral wall extending into the base of the bladder with the prostate having tissue surrounding the urethra near the base of the bladder with a catheter having a control end and a probe end and a passageway extending from the control end to the probe end along a longitudinal axis. A flexible stylet assembly is slidably mounted in the passageway in the catheter and has a distal extremity. The stylet assembly includes a conductive electrode and a sleeve of insulating material surrounding the conductive electrode and permitting a predetermined portion of the conductive electrode to be exposed. A control device is secured to the stylet assembly and to the control end of the catheter for causing movement of the distal extremity of the stylet assembly between a retracted position disposed within the passageway and an extended position disposed outwardly from the probe end whereby the stylet assembly can extend through the urethral wall into the tissue of the prostate with the conductive electrode being disposed in the tissue of the prostate and the sleeve being disposed in the urethral wall. A radio frequency generator is coupled to the conductive electrode for supplying radio frequency energy to the conductive electrode for causing ablation of tissue in the prostate while the urethral wall is protected from the radio frequency energy supplied to the electrode.

This application is a continuation of application Ser. No. 08/012,370filed Feb. 2, 1993, now U.S. Pat. No. 5,370,675, which is acontinuation-in-part of application Ser. No. 07/929,638 filed Aug. 12,1992, abandoned in favor of file wrapper continuation application Ser.No. 08/172,014 filed Dec. 22, 1993, now U.S. Pat. No. 5,366,490.

FIELD OF THE INVENTION

This invention is directed to a unique device and method for penetratingbody tissues for medical purposes such as tissue destruction and fluidsubstance delivery, for example. The device penetrates tissue to theprecise target selected in order to deliver energy to the tissue and/ordeliver substances. It limits this activity to the precise preselectedsite, thereby minimizing trauma to normal surrounding tissue andachieving a greater medical benefit. This device is a catheter-likedevice for positioning a treatment assembly in the area or organselected for medical treatment with one or more stylets in the catheter,mounted for extension from a stylet port in the side of the catheterthrough surrounding tissue to the tissue targeted for medical activity.

BACKGROUND OF THE INVENTION

Treatment of cellular tissues usually requires direct contact of targettissue with a medical instrument, usually by surgical proceduresexposing both the target and intervening tissue to substantial trauma.Often, precise placement of a treatment probe is difficult because ofthe location of a target tissue in the body or the proximity of thetarget tissue to easily damaged, critical body organs, nerves, or othercomponents.

Benign prostatic hypertrophy or hyperplasia (BPH), for example, is oneof the most common medical problems experienced by men over 50 yearsold. Urinary tract obstruction due to prostatic hyperplasia has beenrecognized since the earliest days of medicine. Hyperplastic enlargementof the prostate gland often leads to compression of the urethra,resulting in obstruction of the urinary tract and the subsequentdevelopment of symptoms including frequent urination, decrease inurinary flow, nocturia, pain, discomfort, and dribbling. The associationof BPH with aging has been shown to exceed 50% in men over 50 years ofage and increases in incidence to over 75% in men over 80 years of age.Symptoms of urinary obstruction occur most frequently between the agesof 65 and 70 when approximately 65% of men in this age group haveprostatic enlargement.

Currently there is no proven effective nonsurgical method of treatmentof BPH. In addition, the surgical procedures available are not totallysatisfactory. Currently patients suffering from the obstructive symptomsof this disease are provided with few options: continue to cope with thesymptoms (i.e., conservative management), submit to drug therapy atearly stages, or submit to surgical intervention. More than 430,000patients per year undergo surgery for removal of prostatic tissue in theUnited States. These represent less than five percent of men exhibitingclinical significant symptoms.

Those suffering from BPH are often elderly men, many with additionalhealth problems which increase the risk of surgical procedures. Surgicalprocedures for the removal of prostatic tissue are associated with anumber of hazards including anesthesia associated morbidity, hemorrhage,coagulopathies, pulmonary emboli and electrolyte imbalances. Theseprocedures performed currently can also lead to cardiac complications,bladder perforation, incontinence, infection, urethral or bladder neckstricture, retention of prostatic chips, retrograde ejaculation, andinfertility. Due to the extensive invasive nature of the currenttreatment options for obstructive uropathy, the majority of patientsdelay definitive treatment of their condition. This circumstance canlead to serious damage to structures secondary to the obstructive lesionin the prostate (bladder hypertrophy, hydronephrosis, dilation of thekidney pelves, etc.) which is not without significant consequences. Inaddition, a significant number of patients with symptoms sufficientlysevere to warrant surgical intervention are poor operative risks and arepoor candidates for prostatectomy. In addition, younger men sufferingfrom BPH who do not desire to risk complications such as infertility areoften forced to avoid surgical intervention. Thus the need, importanceand value of improved surgical and non-surgical methods for treating BPHis unquestionable.

High-frequency currents are used in electrocautery procedures forcutting human tissue especially when a bloodless incision is desired orwhen the operating site is not accessible with a normal scalpel butpresents an access for a thin instrument through natural body openingssuch as the esophagus, intestines or urethra. Examples include theremoval of prostatic adenomas, bladder tumors or intestinal polyps. Insuch cases, the high-frequency current is fed by a surgical probe intothe tissue to be cut. The resulting dissipated heat causes boiling andvaporization of the cell fluid at this point, whereupon the cell wallsrupture and the tissue is separated.

Destruction of cellular tissues in situ has been used in the treatmentof many diseases and medical conditions alone or as an adjunct tosurgical removal procedures. It is often less traumatic than surgicalprocedures and may be the only alternative where other procedures areunsafe. Ablative treatment devices have the advantage of using adestructive energy which is rapidly dissipated and reduced to anon-destructive level by conduction and convection forces of circulatingfluids and other natural body processes.

Microwave, radiofrequency, acoustical (ultrasound) and light energy(laser) devices, and tissue destructive substances have been used todestroy malignant, benign and other types of cells and tissues from awide variety of anatomic sites and organs. Tissues treated includeisolated carcinoma masses and, more specifically, organs such as theprostate, glandular and stromal nodules characteristic of benignprostate hyperplasia. These devices typically include a catheter orcannula which is used to carry a radiofrequency electrode or microwaveantenna through a duct to the zone of treatment and apply energydiffusely through the duct wall into the surrounding tissue in alldirections. Severe trauma is often sustained by the duct wall duringthis cellular destruction process, and some devices combine coolingsystems with microwave antennas to reduce trauma to the ductal wall. Fortreating the prostate with these devices, for example, heat energy isdelivered through the walls of the urethra into the surrounding prostatecells in an effort to kill the tissue constricting the urethra. Lightenergy, typically from a laser, is delivered to prostate tissue targetsites by "burning through" the wall of the urethra. Healthy cells of theduct wall and healthy tissue between the nodules and duct wall are alsoindiscriminately destroyed in the process and can cause unnecessary lossof some prostate function. Furthermore, the added cooling function ofsome microwave devices complicates the apparatus and requires that thedevice be sufficiently large to accommodate this cooling system.

Application of liquids to specific tissues for medical purposes islimited by the ability to obtain delivery without traumatizingintervening tissue and to effect a delivery limited to the specifictarget tissue. Localized chemotherapy, drug infusions, collageninjections, or injections of agents which are then activated by light,heat or chemicals would be greatly facilitated by a device which couldconveniently and precisely place a fluid supply catheter opening at thespecific target tissue.

OBJECTS AND SUMMARY OF THE INVENTION

It is the principal object of this invention to provide a device andmethod for penetrating tissue, through intervening tissues to theprecise target tissue selected for a medical action such as tissuedestruction and/or substance delivery, limiting this activity to theprecise preselected site, thereby minimizing the trauma and achieving agreater medical benefit.

One principal object of this invention is to provide a device and methodfor tissue destruction of body tissues which delivers the therapeuticenergy directly into a target tissue while minimizing effects on itssurrounding tissue.

Another principal object of this invention is to provide a device andmethod for introducing fluid treatment agents, particularly flowableliquids, with greater precision and ease to a specific location in thebody.

Another object of this invention is to provide a thermal destructiondevice which gives the operator more information about the temperatureand other conditions created in both the tissue targeted for treatmentand the surrounding tissue. In addition, it will provide more controlover the physical placement of the stylet and over the parameters of thetissue destruction process.

In summary, the medical probe device of this invention comprises acatheter having a control end and a probe end. The probe end includes astylet guide housing having at least one stylet port in a side wallthereof and guide means for directing a flexible stylet outward throughthe stylet port and through intervening tissue at a preselected angle toa target tissue. The housing can include an array of such ports. Thepreselected angle is preferably from 20° to 160° with the central axisof the stylet guide housing. The total catheter assembly includes one ormore stylet guide lumena communicating with respective stylet ports anda stylet positioned in each of said stylet guide lumena for longitudinalmovement from the respective port through intervening tissue to targettissues.

The stylet can be an electrical conductor enclosed within anon-conductive layer, the electrical conductor being an radiofrequencyelectrode. Preferably, the non-conductive layer is a sleeve which isaxially or longitudinally moveable on the electrical conductor to exposea selected portion of the electrical conductor surface in the targettissue.

In a still further embodiment, the stylet is a cannula having alongitudinal, central treatment fluid supply lumen extendingtherethrough, and the catheter has a treatment fluid transport lumencommunicating with the treatment fluid supply lumen.

An ultrasound reflector such as a bubble or an ultrasound transducer canbe embedded or otherwise attached to the probe end or a portion of thestylet to provide a signal for use in positioning the catheter andstylet.

When the stylet includes a radiofrequency electrode, optimally, at leastone temperature sensor such as a thermistor or fiber optic cable can beattached to the probe end, stylet guide housing and/or stylet.

In one preferred embodiment, the stylet guide defines a stylet path froman axial orientation in the catheter through a curved portion to alateral orientation at the stylet port, the curved path optionallyhaving a radius which is sufficient to deflect the deployed, extendedstylet to the desired angle, that is, a radius of up to 0.5 cm,depending upon the diameter of the catheter. The stylet guide means candefine a stylet path having a first curved portion extending in adirection away from the stylet port and a second curved portion,continuing from the first curved portion and extending to the styletport.

For deploying a plurality of stylets, the stylet guide means can defineat least two non-intersecting stylet paths from parallel axialorientations in the catheter through curved portions to lateralorientations at stylet ports, the stylet ports having axes forming anangle of up to 180°. For treating prostate lobes in one embodiment, thestylet port axes form an angle of less than 90° and preferably from 50°to 70°.

The non-conductive sleeve can comprise a leading tip, a rigid proximalcontrol section, and a flexible portion extending from the leading tipthe rigid proximal control section, whereby the sleeve can be extendedthrough a curved path from an axial orientation to an orientationextending outward through a stylet port. The leading tip can be taperedinward toward its terminal end. The flexible portion can optionally be aspiral coil. If the spiral coil is made of conductive material, it canbe enclosed in an outer non-conductive material.

The distal portion of the catheter can be more flexible than theproximal portion thereof, facilitating its passage through curved ducts.

In one embodiment, a control handle is attached to the control end ofthe catheter and stylet movement means attached to a stylet and engagingthe handle for longitudinal movement of the stylet in the stylet guidemeans. The stylet movement means comprises manual engagement means fortranslating manual motion into longitudinal motion of the stylet in thestylet guide means.

In embodiments where the electrical conductor has axial movement in thenon-conductive sleeve, a non-conductive sleeve movement means isattached to a non-conductive sleeve and an electrical conductor movementmeans is attached to the electrical conductor enclosed therein. Thenon-conductive sleeve movement means translates manual motion intolongitudinal motion of the non-conductive sleeve in the stylet guidemeans. The electrical conductor movement means translates manual motioninto longitudinal motion of the electrical conductor in thenon-conductive sleeve. The non-conductive sleeve movement means and theelectrical conductor movement means engage the handle for movementthereon. The non-conductive sleeve movement means and the electricalconductor movement means can include separate, adjacent manual movementmeans, mounted on the handle for both separate and coordinated movementthereon. The housing can have at least two parallel longitudinal slotsthrough a wall thereof, the manual movement means each including afinger engaging surface connected to a slide extending through one ofthe longitudinal slots to a connector in the interior of the housing,the connector being attached to a respective non-conductive sleeve orelectrical conductor.

The method of this invention for applying destructive energy to a targettissue comprises first introducing a catheter to a zone adjacent to thetissue to be treated. Then an electrical conductor is moved from thecatheter through surrounding tissue into a target tissue to bedestroyed. The electrical conductor can be a wire or tube comprising aconductive surface surrounded by a non-conductive sleeve for preventingsignificant transfer of energy from the conductor in tissue surroundingthe sleeve. Heat is generated in the target tissue from an electriccurrent or electromagnetic field produced by the electrical conductor.The volume of tissue being treated is controlled by moving thenon-conductive sleeve to expose a selected length of electrode in thebody tissue to be treated, the remaining area of the electrode remainingshielded by the sleeve to protect the intervening tissues. The amountand duration of the energy delivery is also varied to control the volumeof tissue being treated.

The electrical conductor can be positioned using a fiber optic viewingsystem incorporated within the catheter shaft, positioned to facilitatepositioning of the device. Such a system can also include separateoptics for lumination and viewing, and flushing fluid supply conduitsfor flushing the viewing fields.

The electrical conductor can also be positioned in the tissue to betreated using ultrasound imaging from an ultrasound transducerpositioned at a distance from the target tissue or supported by theelectrical conductor or non-conducting sleeve.

The extent of heating can be monitored and controlled during theablative treatment using temperature sensors supported by the electricalconductor or non-conductive sleeve.

In another embodiment of the method of this invention for treating atarget tissue such as the prostate, two flexible stylets from thecatheter are moved through catheter ports in the sidewall of thecatheter and through the urethra wall and surrounding tissue into theprostate target tissue to be treated, the catheter ports having axesforming an angle of less than 180° and for treatment in some tissue,less than 90°.

In a still further embodiment, a grounding plate is placed on the skinto direct the electrical current passing from one or more electrodes ina path through the target tissue to be ablated.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic cross-sectional drawing of the lower male anatomywith one embodiment of the device of this invention in position fortreatment.

FIG. 2 is a side view of the terminal housing portion of the catheter ofthis invention with a plurality of extended stylets.

FIG. 3 is an end view of the terminal housing portion shown in FIG. 2.

FIG. 4 is a side elevational view in section of an alternativeembodiment of a catheter or stylet guide of this invention.

FIG. 5 is a cross-sectional representation of an embodiment of a RFelectrode stylet according to this invention.

FIGS. 6 and 7 are cross-sectional representations of an embodiment ofthe catheter of this invention with a stylet guide system for adjustingthe stylet guide angle.

FIGS. 8 and 9 are detailed schematic cross-sectional views of a RFelectrode stylet shown in FIG. 4 with a partially retracted sleevepositioned to treat tissue targeted for destruction while shieldingintervening tissue from treatment according to the method of thisinvention.

FIG. 10 is a schematic view of the control console, manual cathetercontrol device and catheter according to this invention.

FIG. 11 is an isometric representation of an embodiment of a manualcontrol device of the system of this invention.

FIG. 12 is an isometric representation of an embodiment of a power andcontrol console of the system of this invention.

FIG. 13 is a plan view of an alternative four-probe embodiment of thedevice of this invention.

FIG. 14 is a side elevational of the distal probe end of the deviceshown in FIG. 13.

FIG. 15 is a cross-sectional end view of the probe end of the deviceshown in FIG. 14, taken along the line 15--15.

FIG. 16 is a partial cross-sectional view of the probe end of the deviceof this invention, taken along the 16--16 of FIG. 15.

FIG. 17 is a cross-sectional view of the control end of the device shownin FIG. 13, taken along its central axis.

FIG. 18 is a cross-sectional view of the control end of the device shownin FIG. 17, taken along the line 18--18.

FIG. 19 is a cross-sectional view of the control end of the device shownin FIG. 17, taken along the line 19--19.

FIG. 20 is a side view of the non-conductive sleeve connector of theembodiment show in FIGS. 17 and 18.

FIG. 21 is a cross-sectional view of the non-conductive sleeve connectorshown in FIG. 20, taken along the line 21--21.

FIG. 22 is a side view of the electrical conductor connector of theembodiment shown in FIGS. 17 and 19.

FIG. 23 is a cross-sectional view of the electrical conductor connectorshown in FIG. 22, taken along the line 23--23.

FIG. 24 is a cross-sectional view of the distal end of thenon-conductive sleeve shown in FIGS. 14 and 15, taken along its centralaxis.

FIG. 25 is a top view of a two stylet alternative embodiment of an RFablation catheter of this invention.

FIG. 26 is a top view of one embodiment of a stylet tip of thisinvention.

FIG. 27 is a side view of the single grind electrode tip shown in FIG.26.

FIG. 28 is an end view of the electrode tip shown in FIG. 27.

FIG. 29 is a side view of an alternative double grind electrode tip.

FIG. 30 is an end view of the electrode tip shown in FIG. 29.

FIG. 31 is a top view of the handle portion of the ablation catheter ofFIG. 25.

FIG. 32 is a side view of the handle portion shown in FIG. 31 takenalong the line 32--32 with the bottom cover plate partially removed.

FIG. 33 is a bottom view of the handle portion shown in FIG. 31 with thebottom cover plate removed.

FIG. 34 is a cross-sectional view of the handle portion taken along theline 34--34 in FIG. 33.

FIG. 35 is a cross-section view of the central portion of the handleportion shown in FIG. 32 in the stylet and sleeve retracted position.

FIG. 36 is a cross-sectional view of the central portion of the handleportion shown in FIG. 32 with the stylet and sleeve in an extendedposition.

FIG. 37 is a cross-sectional view of the central portion of the handleportion shown in FIG. 32 with the stylet in an extended position and thesleeve partially retracted therefrom.

FIG. 38 is a schematic view of a deployment of two stylets in a prostateshowing stylet orientation for the overlapping ablation zone method ofthis invention.

DETAILED DESCRIPTION OF THE INVENTION

The device of this invention provides a precise controlled positioningof a treatment stylet in a tissue targeted for treatment, destruction orsampling from a catheter positioned in the vicinity of the targettissue.

The term "stylet" as used hereinafter is defined to include both solidand hollow probes which are adapted to be passed from a catheter portthrough normal tissue to a target tissue. The stylet is shaped tofacilitate easy passage through tissue. It can be a solid wire, thinrod, or other solid shape or it can be a thin hollow tube or other shapehaving a longitudinal lumen for introducing fluids to or removingmaterials from a site. The stylet can also be a thin hollow tube orother hollow shape, the hollow lumen thereof containing a reinforcing orfunctional rod or tube. The stylet preferably has a sharpened end toreduce resistance and trauma when it is pushed through tissue to atarget site.

The stylet can be designed to provide a variety of medically desiredtreatments of a selected tissue. As a radiofrequency electrode, it canbe used to ablate or destroy the target tissue. As a hollow tube, it canbe used to deliver a treatment fluid such as a liquid to a targettissue. The liquid can be a simple solution or a suspension of solids,for example, colloidal particles, in a liquid. Since the stylet is verythin, it can be directed from the catheter through intervening normaltissue with a minimum of trauma to the normal tissue.

The device and method of this invention provide a more precise,controlled medical treatment which is suitable for destroying cells ofmedically targeted tissues throughout the body, both within and externalto body organs. The device and method are particularly useful fortreating benign prostate hyperplasia (BPH), and the device and its useare hereinafter described with respect to BPH, for purposes ofsimplifying the description thereof. It will be readily apparent to aperson skilled in the art that the device and method can be used todestroy body tissues in any body cavities or tissue locations that areaccessible by percutaneous or endoscopic catheters, and is not limitedto the prostate. Application of the device and method in all of theseorgans and tissues are intended to be included within the scope of thisinvention.

BPH is a condition which arises from the benign replication and growthof cells in the prostate, forming glandular and stromal nodules whichexpand the prostate and constrict the opening of the prostatic urethra.Glandular nodules are primarily concentrated within the transition zone,and stromal nodules within the periurethral region. Traditionaltreatments of this condition have included surgical removal of theentire prostate gland, digital removal of the adenoma, as well astransurethral resection of the urethral canal and prostate to removetissue and widen the passageway. One significant and seriouscomplication associated with the latter method is iatrogenic sterility.More recently, laser treatment has been employed to remove tissue,limiting bleeding and loss of body fluids. Balloons have also beenexpanded within the urethra to enlarge its diameter, with and withoutheat, but have been found to have significant limitations.

Microwave therapy has been provided with some success by positioning amicrowave antenna within the prostatic urethra and generating heat inthe tissue surrounding the urethra with a microwave field. Coolants aresometimes applied within the catheter shaft to reduce the temperature ofthe urethral wall. This necessitates complicated mechanisms to provideboth cooling of the immediately adjacent tissues while generating heatin the more distant prostatic tissue. This technique is similar tomicrowave hyperthermia. Similarly, radiofrequency tissue destructionwith electrodes positioned within the urethra has limited applicabilitysince it necessarily exposes the urethral wall to destructivetemperatures. To avoid this, low temperature settings required toprotect the urethra must be so low that the treatment time required toproduce any useful effect is unduly extended, e.g. up to three hours ofenergy application.

One embodiment of the device of this invention uses the urethra toaccess the prostrate and positions RF electrode stylets directly intothe tissues or nodules to be destroyed. The portion of the styletconductor extending from the urethra to the target tissue is enclosedwithin a longitudinally adjustable sleeve shield which prevents exposureof the tissue adjacent to the sleeve to the RF current. Thus theablative destruction is confined to the tissues targeted fordestruction, namely those causing the constriction. Other aspects of theinvention will become apparent from the drawings and accompanyingdescriptions of the device and method of this invention. It will bereadily apparent to a person skilled in the art that this procedure canbe used in many areas of the body for percutaneous approaches andapproaches through body orifices.

FIG. 1 is a schematic cross-sectional drawing of the lower male anatomyduring use of the device and method of this invention. The urethra 2extends from the urinary bladder 4 through the prostate 6 and urogenitaldiaphragm 8. BPH is a condition characterized by constriction of theportion of the prostatic urethra caused primarily by proliferation ofbenign glandular and stroma cells in the prostate. These nodules pressthe wall of the urethra inwardly, restricting the urethral diameter, andcan press normal tissue outwardly, possibly enlarging the prostate.Traditional treatments short of removal of the prostate have includedeither removal of tissue from the urethra to enlarge its lumen byresection or laser tissue destruction, or by expansion and heating ofthe tissue surrounding the urethra to a temperature which causes celldeath. The latter method is intended to reduce the swelling orenlargement of the prostate, and restore the urinary passage to at leasta portion of its former diameter.

In the method of this invention, a catheter 14 with a stylet guide 16 ispassed upwardly through the urethra into the prostate. The position ofthe guide 16 is precisely controlled, using an ultrasound image, forexample, obtained from signals received from the conventional ultrasoundtransducer 18 inserted into the rectum 20 adjacent to the prostatethrough the anal opening 22. The guide 16 facilitates easy positioningof the stylet 17 into a precise location under ultrasound imaging.Optionally, fiber optics can be used to position the stylet guide.

The terminal portion of the catheter 14 can optionally have one or moredilation balloons 30 and 32. Stylet sleeve 36 can be extended throughthe urethra and other tissue to be protected, and an RF electrode 38, asshown for example in this figure, can be extended deep into the targettissue 28.

FIG. 2 is a side view and FIG. 3 is an end view of the terminal portionof one embodiment of a catheter of this invention. One or more styletports 40 are positioned between the unexpanded annular balloons 30 and32. An ultrasound transponder 42 can be positioned at the terminal end44 for producing signals and images which can be used for precisepositioning of the stylet guide 16 in the prostate. Alternatively, anechogenic bubble (not shown) can be incorporated into the distal housingto aid in sonographic location of the stylet guide. One or moretemperature sensors 46, which can be conventional thermistors,thermocouples or optical fibers, are positioned along the catheter orstylet guide 16 to provide a temperature profile of the urethra adjacentto and preferably on both sides the stylet guide 16. This temperatureprofile can be used by the operator to prevent the temperature of theurethral wall from reaching a level which would cause cell destruction.FIGS. 2 and 3 show both balloon segments 30 and 32 and six stylets 36corresponding to the stylet 17 in an extended position.

The catheter or stylet guide 16 can be rotated about its central axisprior to stylet deployment to orient one or more of the stylets 36toward tissues to be treated. After the distal extremity of the styletguide catheter 16 is advanced to a treatment position in the prostaticurethra, the annular balloons 30 and 32 can be expanded in the urethrato stabilize the catheter or stylet guide 16 and dilate the urethrallumen. The stylets 36 are extended through the urethral wall andintermediate tissue until they are positioned in the tissue targeted fortreatment. The tissue targeted for BPH treatment may be nodules, normaltissue or both. The stylet passageways leading to ports 40 have anorientation such that their terminal axis forms an angle "a" which canbe from about 20° to 160° and preferably from about 30° to 150° with thecentral axis of the catheter in a plane therethrough. As will beexplained in greater detail hereinafter with regard to one embodiment ofthis invention, a non-conducting sleeve is then moved to expose thetarget tissue to controlled heating by an electric current to adestructive temperature above 45° C. and preferably within the range offrom 55° to 99° C.

In the embodiment of the catheter or stylet guide shown in FIGS. 4 and 5the catheter or stylet guide 48 is connected to a stylet guide housing50 having a nose 52. A flexible stylet 54 comprises a solid core needle56 (see FIG. 5) coaxially positioned within a tube 58, both of which arepreferably constructed of a highly flexible, conductive metal such as anickel-titanium alloy, tempered steel, stainless steel, beryllium-copperalloy and the like. Nickel-titanium and similar highly flexible, shapedmemory alloys are preferred. The needle 56 is axially or longitudinallymovable within the tube 58. The tube 58 is enclosed within annon-conductive, sleeve 60 which is longitudinally movable along the tube58. The guide housing 50 has a guide channel 61 (see FIG. 4) which iscurved to permit longitudinal advancement of the flexible stylet.

The sleeve 60 is connected to an annular cylinder 62 connected with alongitudinal thrust tube 64. Longitudinal movement of the thrust tube 64causes a corresponding longitudinal movement of the sleeve 60 along thetube 58. The sleeve movement is used to vary and control the length oftube 58 and needle 56 exposed to surrounding tissue and control theamount of energy delivered to the target tissue. The material,insulating properties, dielectric properties and thickness of the sleeve60 are selected to prevent heating energy delivery to tissue in contacttherewith by shielding the tissue from the conductor. If the tissue isto be heated using radiofrequency current (300 to 750 kHz), the sleeve60 must have sufficient thickness required to prevent both current flowand capacitance coupling with the tissue.

An alternative embodiment of a catheter or stylet guide 124 is shown inFIG. 6 and as shown consists of a stylet guide housing 125 having astylet port 126. A stylet positioning block 128 is positioned within thehousing 125 for axial movement under the action of a torque and thrustrod 130. The stylet positioning block 128 has a curved stylet lumen 131containing a stylet 132. Optionally, a low friction, flexible guidetubing 134 extends from the positioning block 128 to the port 126. Inthe position shown in FIG. 6, the positioning block 128 is in aretracted position, orienting the stylet to extend at an acute angle "b"of approximately from about 20° and preferably 30° up to 90° withrespect to the central axis of the guide housing. Advancement of thestylet 132 through the block 128, guide tubing 134 and port 126 directsthe stylet into tissue along the dotted line path 136.

Advancement of the positioning block 128 as shown in FIG. 7 forces thestylet 132 through a curved path having a smaller diameter through guidetubing 134 to the port 126. The stylet 132 is then directed an obtuseangle b which can be as high as about 160° with respect to the guidehousing axis. Advancement of the stylet through the guide block 128,guide tubing 134 and port 126 in this configuration directs the styletinto tissue along the dotted line path 138 shown in FIG. 8.

As shown in FIGS. 6 and 7, the angular projection of the stylet 132 canbe oriented over a wide range of angles in a plane through the centralaxis of the stylet guide housing 125. It will be readily apparent thatrotation of the torque and thrust rod 130 about its central axis willcause a corresponding rotation of the stylet guide housing 125 anddeflection of the stylet 132 in directions outside of the axial plane.This combined with axial movement of the catheter or stylet guide 124 toan optimum position in a duct and rotation of the catheter or styletguide 124 about its central axis yields an infinite variety of styletorientation angles. A combination of these movements provides greaterchoices of stylet angles so that the stylet can be advanced into targettissue at any angle from the catheter.

After the catheter or stylet guide 48 shown in FIGS. 5 and 6 ispositioned in the urethra as shown in FIG. 9, the stylet 54 is advancedfrom the stylet guide housing 50 through the prostatic urethra wall 71to the target tissue 73 to be treated (outlined with a dotted line).Then, stylet sleeve 60 is retracted to the position shown in FIG. 8,exposing the portion of the RF electrode positioned in the target tissue73. RF current is then directed from the electrode 56 and 58 throughtissue 73 to conventional grounding plates (not shown) serving as anindifferent electrode. In selected instances, more directed ablation canbe obtained by using one or more of the stylets as the indifferentelectrode and another of the styles as the active electrode, therebyusing only stylets to complete the dipole and not using a groundingplate. The RF treatment is continued until the cells in the targettissue 73 have been destroyed.

FIG. 9 is a detailed schematic cross-sectional view corresponding toFIG. 8 in an optional second step following the procedure describedabove in connection with FIG. 8. Following destruction of the cells intarget tissue 73, the RF electrode sleeve 60 can be retracted along thestylet electrode 58 to the stylet guide housing 50, exposing a length ofRF electrode 74 leading from the target tissue through prostatic urethrawall 71. Sufficient RF current is then applied to cauterize the surfaceof the tissue 76 (shown by dotted lines) immediately in contact with theentire exposed surface of the electrode 58. For example, this can beachieved with a higher voltage and shorter duration treatment than isapplied to destroy the cells of the target tissue. The stylet is thenfully withdrawn into the housing 50, leaving a drainage duct leadingfrom the area of the target tissue 73 to the prostatic urethra. This canprovide drainage of the products of the treated target tissue 73 duringthe healing process.

The transurethral needle ablation (TUNA) process of this invention is aprocess whereby a physician in a unique procedure deliversradiofrequency to the hyperplastic tissues of the prostate which developin men with the condition known as BPH, or Benign Prostatic Hyperplasia.This procedure is unique in that it is the first transurethral procedurewhich selectively provides the ability to limit the treatment to theconstrictive tissue and spare the normal prostatic tissue. Thisprocedure also minimizes the trauma sustained by the surroundingprostatic urethra, especially when compared to previously knownprocedures for relieving obstructive uropathy due to BPH. The procedurecould possibly be carried out under local anesthesia only, dependingupon the rate of energy delivery and degree of pain sensationexperienced by the patient. When local anesthetic is adequate, theprocedure can be performed in the physician's office. Local anestheticcould be delivered or applied in the form of a lubricant containing atopical anesthetic such as lidocaine mixed with K-Y jelly.

If substantial pain will be experienced by the patient, the patient mustbe sedated in addition to application of topical local anesthetic. Thisprocedure can be provided on an outpatient basis and would require ashort term (2-6 hour) observation. If the procedure and patient requiregreater pain control, then spinal anesthesia or a general anesthesia maybe used for patients which qualify for their use. This would mandatethat the procedure be carried out in the operating room, would require arecovery room, and could possibly require in-patient care in certaincircumstances. The previously known prostate resection (TURP) generallyrequires use of general or spinal anesthesia and in-patient hospitalcare following the treatment.

The BPH method of this invention can be carried out in the followingmanner, using a RF electrode stylet embodiment of this invention. A malepatient is given the appropriate pre-procedure preparation which wouldusually require a fleets enema or bowel preparation. This would clearthe rectal vault of stool in order to better place a rectal ultrasoundprobe, if used, and to assure better visualization. Appropriateanesthetic, would then be administered. A conventional grounding plateis then placed in contact with the patient. The rectal probe would thenbe inserted to the level of the prostate in order to obtain anultrasound image of the prostate. The procedure could be done withoutthe use of rectal ultrasound, using only direct visualization at thediscretion of the operator. The urethral catheter would then be insertedin a fashion similar to that used for inserting a Foley catheter. Firstthe glans and the penile shaft would be bathed in betadine or otherdisinfectant. The rest of the groin adjacent areas are draped withsterile towels in the usual fashion. Then using aseptic or steriletechnique, the shaft of the penis is grasped in one hand while thecatheter is inserted into the urethral meatus and advanced until it hasreached to desired position in the prostatic urethra. The cathetermovement during its advancement through the urethra can be monitoreddirectly with the ultrasound image. If direct visualization with fiberoptics is used, the appropriate landmarks are located and identified,i.e., verumontanum and bladder neck, etc. If this has not beenaccomplished earlier, the various electrical and mechanical connectionsbetween the catheter and the control assembly are connected at thisstage.

The RF electrode stylet is then deployed under direct vision orultrasound imaging into a selected target tissue. This requires that thephysician locate the target area to be treated, rotate, advance and/orretract the catheter as necessary to orient the stylet guide port towardthe target area. The stylet, preferably completely surrounded in itsinsulating sleeve or sheath, punctures and penetrates the epitheliallining of the prostatic urethral, traveling through prostatic tissue tothe target tissue, and penetrating the tissue to the desired depth.Local anesthetic can be infiltrated into the target tissue through thecentral lumen of the stylet as the stylet is advanced. The insulatingsleeve is then retracted the amount required to expose a preciseselected length of the RF electrode in the target tissue. This amount isselected to effect the degree and volume of tissue destruction desired,the volume increasing as the length of the exposed electrode increases.This volume is selected based on the size of the target tissue to beablated and the relative position of the electrode stylet in the targettissue. The distance the sleeve is withdrawn can be measured external tothe body using a conventional measuring devices such as a scale.

The electrode stylet is then energized from an RF energy source byclosing a conventional switch. Preferably, the time and/or power levelsare preset by the control unit. The RF energy is delivered to the targettissue for a preselected time, monitoring the advance of the destructivelesion by the rectal ultrasound image. Impedance is also monitored, andwhen or if it exceeds a preset value, the power supply can be reduced orterminated. The temperature of the catheter surface adjacent theurethral lining, the sleeve and even the exposed electrode can also bemonitored using temperature sensors attached to these components toprecisely control the volume of the lesion and prevent excessive heatingof normal tissue.

After the target tissue destruction has proceeded to the desired stage,the physician has two options. The stylet electrode can be withdrawninto the catheter to facilitate quick healing and rapid sealing of theurethral puncture site. Alternatively, the physician can create atemporary physiological drainage capillary which would allow any fluidor debris accumulating in the ablated target tissue to drain into theurethra. This physiological drainage capillary can be created aftertarget tissue destruction by withdrawing the insulating sleeve or sheathback into the urethral catheter as shown in FIG. 9. The conductivestylet is then energized to a level sufficient to "sear" or cauterize asmall hollow channel through the tissue. This channel will eventuallyscar and fibrose, or it will seal and heal. The conductive stylet isthen entirely withdrawn, and the catheter is slowly and carefullywithdrawn from the urethra. The patient is then monitored and treated asappropriate for the type of anesthesia delivered and the condition ofthe patient.

FIG. 10 is a schematic view of the assembly of the power and controlsystem 150, a manual catheter control unit 152, catheter 154, and powerfoot control 156. The power foot control functions can be accomplishedby numerous other methods to include manual digital switches on controlbox 150 and by a trigger device on the catheter handle 152. The manualoperation of the catheter assembly is controlled from a manual controlunit shown in greater detail in FIG. 11, with the power control andtemperature displays being provided in the control system 150 shown ingreater detail in FIG. 12.

FIG. 12 is an isometric representation of an embodiment of a manualcontrol system of the system of this invention. The manual control 152has a pistol grip 158 with a tube 160 leading to the console shown inFIG. 13. The tube 160 houses RF power supply cables, temperaturesensors, ultrasound transducer power and signal delivery leads, ballooninflation fluid and vacuum lumens.

Rocker switches 162 and 164 provide control over the inflation ordeflation of balloons 30 and 32 (FIGS. 1 and 2). Tab 166 sliding ingroove 168 is connected to a stylet 62, advancing it into the a targettissue as the tab 166 is moved forward. Rotary dial 170 is attached tothe catheter 154 and can be used to rotate the catheter for orientationof the stylet or stylets. Window 172 has graduations showing thepercentage of balloon expansion.

FIG. 12 is an isometric representation of an embodiment of a power andcontrol console 150 of the system of this invention. The housing of thisconsole has a display panel 174 with digital readout displays 176showing power to the stylet, antenna temperatures, tissue temperatures,impedance values, and other data, for example. The housing can support asealed membrane switch panel 178 having system control buttons 179.Power cord 180 leads to a standard power outlet. Cable 182 leads to themanual catheter control unit 152 shown in FIG. 11. Cable 184 leads to aoptional power foot control unit. Cable 185 leads to the grounding patchfor use in unipolar systems.

FIG. 13 is a view of an alternative four-probe embodiment of the deviceof this invention. The device comprises a handle portion 180 and acatheter portion 182. The catheter portion 182 includes an elongatedcatheter 184 having a distal catheter probe end 186. A plurality ofstylets 188 extend outwardly from the probe end 186. The end 190 of thehandle portion 180 is attached to the proximal end of the catheter 182,and manual control tabs 192 and 194 mounted thereon for slidingengagement with side walls of the handle portion. Using the handle 180for control, the catheter is introduced into a body duct, vascularstructure or canal such as the urethra, for example, and pushed up theduct to the treatment position, for example a position adjacent theprostate. Stylets 188 are individually and selectively passed outwardfrom the distal end 190 through surrounding tissue to the target tissueto be treated by movement of respective manual control tab pairs 192 and194. When the stylets are electrical conductors surrounded by movablesleeves, the sleeves can be retracted from the end of the stylets bymovement of manual control tabs 194 as described in greater detailhereinafter. Preferably, the proximal portion of the catheter 182 ispreferably stiff to facilitate control during insertion in a body duct,while the distal portion is preferably flexible to allow the catheter topass through curved duct portions.

FIG. 14 is a side partially sectioned view of the distal probe end ofthe catheter shown in FIG. 13 with stylets extended from the side ports,and FIG. 15 is a cross-sectional end view of the probe end of the deviceshown in FIG. 14, taken along the line 16--16. The distal catheter tip186 is a stylet guide housing having a lateral surface 196 which mergeswith a tapered tip portion 198. The stylets 188 extend outwardly fromthe lateral surface 196 and comprise an electrode 200 and movablesurrounding sleeve 202. The proximal portion 204 of the stylet guide isconnected to the distal end 206 of the catheter stem 208. Further styletports such as the port from which stylet 203 extends are positioned at agreater distance from the tip 198 than ports 216. The embodiment shownin FIGS. 14 and 15 comprises two sets of stylets, each pair extendingfrom ports in a common plane perpendicular to the catheter central axis.It will be readily apparent to a person skilled in the art that otherstylet arrays such as a longitudinal array or a spiral array can also beused, and these variations are considered to be fully within the scopeof this invention.

The catheter stem 208 includes an outer tubular housing 210 whichencloses a plurality of stylets stems 212 disposed in a parallelrelationship. As can be seen from FIG. 15, the individual stylets aredirected outward in paths which have axes forming angles with eachother. Oppositely disposed stylets can form an angle of up to 180° whilein the configuration shown, the axis of adjacent stylets can form anangle of up to 90° for example.

FIG. 16 is a partial cross-sectional view of the probe end of the deviceof this invention, taken along the 17--17 of FIG. 15. The stylet isdirected through a stylet guide means 214 in the distal catheter end 186which leads from a path in the proximal end 204 of the stylet guidemeans parallel with other stylet guides to a lateral orientation throughstylet port 216. To facilitate longitudinal movement of the styletthrough the guide path, the guide path preferably has a curved portion218 extending to the port 216. The curved path optionally has a radiuswhich is sufficient to deflect the deployed, extended stylet to thedesired angle, that is, a radius of up to 0.5 cm, depending upon thediameter of the catheter. Optimally, the guide path also has a reversecurved portion 220 which extending from the axially parallel path in theproximal catheter end 214 outwardly away from the port 216 to thebeginning of the curved path 218.

The distal tip 198 of the catheter can have a hollow space or bubble 222which reflects ultrasound, permitting its easy identification withultrasound generated by a rectal probe as shown in FIG. 1.Alternatively, a transponder can be mounted in the distal tip 198.

FIG. 17 is a cross-sectional view of the handle and control end of thedevice shown in FIG. 13, taken along its central axis. The controlhandle 180 is attached to the control end of the catheter stem 208. Thehandle 180 comprises a housing having a distal end forming an axialsleeve 224 enclosing the proximal end 226 of the catheter stem 208. Theproximal end 226 is held in place by setscrew 228 extending through thesleeve 224. Manual engagement means 192 and 194 engage lateral handlehousing walls 230 and 232, and are mounted for sliding engagement withrespective slots 234 and 236 in the respective housing walls. Theytranslate the manual motion into longitudinal motion of the stylet inthe stylet guide means.

FIG. 18 is a cross-sectional view of the control end of the device shownin FIG. 13, taken along the line 18--18 of FIG. 17.

FIG. 18 is a cross-sectional view of the control end of the device shownin FIG. 13, taken along the line 18--18 of FIG. 17. Referring to bothFIGS. 17 and 18, finger engaging sleeve movement tabs 192 are connectedto connecting slide portion 238 extending through a respectivelongitudinal slot 234 and a inner portion 240 which forms a slidingengagement with the interior surface of the handle wall 230. Slot 242 inthe connecting slide portion receives a pin 244 extending through asleeve connector 246. Axial movement of the tab 192 thus effects anaxial movement of corresponding sleeve 248 in the handle. Each side ofthe handle can have a pair of longitudinal, parallel slots toaccommodate manual tabs for both sleeve and electric conductor.

FIG. 19 is a cross-sectional view of the control end of the device shownin FIG. 13, taken along the line 19--19 of FIG. 18. Referring to FIGS.17 and 19, finger engaging electrical conductor movement tab 194 isconnected through a connecting slide portion 250 extending through arespective longitudinal slot 236 to a inner portion 252 which forms asliding engagement with the interior surface of the handle wall 232.Slot 254 receives a pin 256 extending through a electrical conductorconnector 258. Axial movement of the tab 194 thus effects an axialmovement of the corresponding electrical conductor 260 in the handle.

Movement of adjacent tabs 192 and 194 advance the corresponding sleeveand electrical conductor together through the corresponding styletguide, out the corresponding stylet port, and through intervening tissueto the target tissue to be ablated. Reverse movement of the sleeve tab192 then retracts the sleeve to expose a selected area of the electricalconductor surface in the tissue, preparatory to ablation.

FIG. 20 is a side view of the non-conductive sleeve connector of theembodiment show in FIGS. 17 and 19, and FIG. 21 is a cross-sectionalview of the non-conductive sleeve connector shown in FIG. 20, takenalong the line 22--22. Connecting pin 244 extends through a hole in thesleeve connector 246. An axial edge of the sleeve connector 246 isconnected to the proximal end portion 248 of the sleeve.

FIG. 22 is a side view of the electrical conductor connector of theembodiment show in FIGS. 17 and 19, and FIG. 23 is a cross-sectionalview of the electrical conductor connector shown in FIG. 22, taken alongthe line 24--24. Connecting pin 256 extends through a hole in theelectrical conductor connector 258. An axial edge of the electricalconductor connector 258 is connected to the proximal end portion 260 ofthe electrical conductor.

FIG. 24 is a cross-sectional view of the distal end of thenon-conductive sleeve shown in FIGS. 15-17, taken along its centralaxis. The non-conductive sleeve 202 comprises a tapered leading tip 262and a rigid proximal portion 264. A flexible portion 266 extends betweenthe leading tip 262 to the rigid proximal portion 264. The flexibleportion 266 can be any flexible configuration such as a spiral coil,wire braid, stainless steel tube, or any other flexible constructionwhich yields a catheter which has the required flexibility and torquestrength. If the flexible portion 266 and the rigid proximal portion 264are made of a conductive materials such as metal, they can be coveredwith an insulating sleeve 268. The annular ridges 270 in the rigidproximal portion and the flange 272 in the tip engage the sleeve 268,securing the sleeve in place., The inner lumen 274 of the non-conductivesleeve 202 receives the electrical connector 200. A temperature sensorsuch a thermistor 271 can be mounted on the tip to provide localtemperature information. An ultrasound transponder 273 can also bemounted on the tip to provide a signal useful for precise positioning ofthe stylet tip in a tissue to be ablated.

FIG. 25 is a top view of a two stylet preferred embodiment of an RFablation catheter of this invention. The flexible catheter 300, attachedto handle 302, has a terminal stylet guide 304 with two stylets 306 and308. The handle has stylet sleeve tabs 356 and electrode tabs 358 aswill be described in greater detail hereinafter. The handle is alsoconnected to a visual monitor 301 and RF power connector 303,transponder connector 305 and thermocouple connector 307. The portion ofthe catheter 300 leading from the handle 302 to the stylet guide tip 304can optionally has a graduated stiffness. For example, the catheter canbe designed to be more stiff near the handle and more flexible near thetip, or any other stiffness profiles. The catheter can be constructed ofan inner slotted stainless steel tube with outer flexible sleeve such asis described in U.S. Pat. No. 5,322,064, the entire contents of whichare incorporated herein by reference. It can also be made of coiled orbraided wire to which an outer sleeve is bonded.

FIG. 26 is a top view of the stylet tip of the embodiment shown in FIG.25, FIG. 27 is a side view of the single grind electrode tip shown inFIG. 26, and FIG. 28 is an end view of the electrode tip shown in FIG.27. In this embodiment, the sharpened tip 326 of electrode 337 andleading cutting edges 328 and 330 are formed by grinding one surface ofthe tip, the cutting edges forming an angle, "d", of from 15° to 45° andpreferably from 25° to 35° with a line parallel with the central axis ofthe tip. The proximal surface of the tip forms a shoulder 332 which theleading or distal edge 334 of the sleeve 336 abuts, preventing movementof the sleeve 336 over the sharpened tip. The sleeve 336 can alsosupport temperature sensors such as a thermistor 338 and a ultrasoundtransponder 340.

FIG. 29 is a side view of an alternative double grind electrode tip, andFIG. 30 is an end view of the electrode tip shown in FIG. 29. In thisembodiment, the sharpened tip 342 and leading cutting edges 344 and 346of electrode 341 are formed by grinding both surfaces of the tip. Theproximal surface of the tip forms a shoulder 348 which the leading ordistal edge of a sleeve (not shown) abuts, preventing movement of thesleeve over the sharpened tip. The forward cutting edges of thisembodiment make little if any contact with the inner surface of thestylet guide in the catheter tip, preventing dulling of the cuttingedge.

FIG. 31 is a top view of the handle portion of the ablation catheter ofFIG. 25. The handle 302 has an upper housing plate 350 upon which styletsleeve positioning slides 352 and electrode positioning slides 354 withmanual tabs 356 and 358 are mounted for sliding movement in thedirection of the central axis of the housing. The position of theleading edges 360 of the slides relative to the graduated markings 362on the housing plate surface are used to determine the distance thesleeve and stylet have been advanced from the stylet guide toward tissueto be treated.

FIG. 32 is a side elevational view of the handle portion shown in FIG.31 taken along the line 32--32 with the bottom housing cover platepartially removed. The proximal end of the catheter 300 passes through acylindrical hole 364 in the cylindrical knurled knob 366 and cylindricalreceptor 368 formed by the opposed hemicylindrical surfaces in thedistal ends of the upper housing plate 350 and lower housing plate 370.The proximal end of the knurled knob 366 has a cylindrical receptor 372which forms a sliding fit with a cylindrical projection 374 formed bythe distal ends of the housing plates 350 and 370. Setscrew 376 securesthe knob 366 to the catheter 300 so they rotate together as a unit. Pin378 extends through the knob 366 into an annular groove 380, allowingrotation but preventing axial movement of the knob 366 relative to thecylinder 374. The angular position of the knob 366 relative to thehousing plate 350 is shown by the position of the arrow 382 relative tothe graduations 384 on the knob (FIG. 31). Knurled knob 386 treadinglyengages hole 388 in the housing plate 350. When the catheter knob 366has been turned to rotate the catheter 300 (and the stylet guide on itsend) to a desired stylet orientation, advancement of the knob 386against the catheter surface 390 secures its angular position. Thestylets are then advanced through surrounding tissue to the depthdesired, as indicated by graduations 362.

FIG. 33 is a bottom view of the handle portion shown in FIG. 31 with thecatheter, distal knob and bottom cover plate removed, and FIG. 34 is across-sectional view of the handle portion taken along the line 34--34in FIG. 33. Stylet movement guide plates 392 and 394 are securelymounted in terminal end receptors 396 in the inner surfaces of upperhousing plate 350. Each of the guide plates 392 and 394 has a sleeveguide slot 398 and a electrode guide slot 400 therein. Screws 402 extendthrough sleeve guide slots 400 and threadingly engage the sleeve guideblocks 404. Axial movement of the screws 402 and guide blocks 404attached thereto is limited by the length of the slots 398. Sleeveconnector 406 attached to stylet sleeve 408 is secured to the guideblock 404 by screw 410. Slide plate 412 mounted for sliding movement ina slot 414 in the housing plate 350 is secured to guide block 404.Screws 416 extend through sleeve guide slots 400 and threadingly engagethe electrode guide blocks 418. Axial movement of the screws 416 andguide blocks 418 attached thereto is limited by the length of the slots400. Electrode connector 420 attached to stylet electrode 422 is securedto the guide block 418 by screw 424. Slide plate 354 mounted for slidingmovement in a slot 426 in the housing plate 350 is secured to guideblock 418.

FIG. 35 is a cross-sectional view of the central portion of the handleportion shown in FIG. 32 in the stylet and sleeve retracted position(corresponding to the positions in FIG. 31). FIG. 36 is across-sectional view with the stylet and sleeve in an extended position,and FIG. 37 is a cross-sectional with the stylet in an extended positionand the sleeve partially retracted therefrom. The stylets are extendedafter the catheter is inserted to place the stylet guides in a positionlaterally adjacent the target tissue to be treated and the catheter hasbeen rotated to orient the stylet guide outlets in the direction of thetarget tissue. The stylets are extended through intervening tissue tothe target tissue by moving the manual tabs 356 and 358 toward thedistal end of the handle as shown in FIG. 36. This effects simultaneousmovement of the stylet sleeve 408 and electrode 422. After the extensionhas proceeded to the extent required to place the tip of the electrode422 in the target tissue, the sleeve 408 is retracted to the positionshown in FIG. 37 by moving the manual tab 356 in the proximal directionto the extent required to expose the desired portion of the electrode asindicated by graduations 362 (FIG. 31). The RF current is then appliedto the electrodes until the desired ablation has been achieved. Withthis embodiment, two stylets can be extended, sleeves retracted, and theablation achieved either concurrently or sequentially.

FIG. 38 is a schematic view of a deployment of two stylets in a prostateshowing stylet orientation for overlapping ablation zone method of thisinvention. For purposes of illustration but not by way of limitation,the prostate has been selected for this explanation, and application ofthis method and assembly to other areas of the body are intended to beincluded.

The tissues to be treated for the treatment of BPH are located in thetransition zone 428 of the prostate. A catheter of this invention 430has been inserted up the urethra 432 to a position adjacent theprostate. Two stylets 434 and 436 have been passed through the urethralwall 432 and surrounding tissue into the target tissue, and thenon-conducting sleeves 438 and 440 have been retracted to expose aportion of the respective electrical conductors 442 and 444 at the endof each stylet. The angle between the axes of the stylets in thisembodiment, "e", is less than 180°, preferably less than 110°. For mostoverlapping ablations, angles of 15° to 90°, and more usually from 20°to 70° are most practical. A grounding plate (not shown) is placed onthe body exterior.

When electrodes 442 and 444 are supplied with RF current, the circuitfrom the electrodes to a grounding plate is closed. The current densityflowing through the tissue passes through the target tissue to betreated, creating lesions having the approximate cross-sectional shapeof overlapping zones 446 and 448. The current density rapidly decreasesas a function of distance, limiting the size of the lesions. In thismanner, lesions can be caused to overlap to form a larger lesion,increasing the efficiency of the treatment. It will be readily apparentthat these processes can be carried out concurrently, as described, orsequentially, and these variations are intended to be included in thisinvention.

Although preferred embodiments of the subject invention have beendescribed in some detail, it is understood that obvious variations canbe made without departing from the spirit and the scope of the inventionas defined by the appended claims.

We claim:
 1. A medical probe device for treatment of a prostate of ahuman male having a bladder with a base with a urethra formed by aurethral wall extending into the base of the bladder with the prostatehaving tissue surrounding the urethra near the base of the bladdercomprising a catheter having a control end and a probe end and apassageway extending from the control end to the probe end along alongitudinal axis, a flexible stylet assembly slidably mounted in thepassageway in the catheter and having a distal extremity, said styletassembly comprising a conductive electrode and a sleeve of insulatingmaterial surrounding the conductive electrode and permitting apredetermined portion of the conductive electrode to be exposed, controlmeans secured to the stylet assembly and to the control end of thecatheter for causing movement of the distal extremity of the styletassembly between a retracted position disposed within the passageway andan extended position disposed outwardly from the probe end whereby thestylet assembly can extend through the urethral wall into the tissue ofthe prostate with the conductive electrode being exposed in the tissueof the prostate and the sleeve being disposed in the urethral wall andmeans coupled to the control means and to the conductive electrode forsupplying radio frequency energy to the conductive electrode for causingablation of tissue in the prostate while the urethral wall is protectedfrom the radio frequency energy supplied to the electrode.
 2. A medicalprobe device as in claim 1 together with means connected to the controlmeans for causing relative movement between the sleeve of insulatingmaterial and the conductive electrode to expose said predeterminedportion of the conductive electrode.
 3. A medical probe device as inclaim 1 wherein the conductive electrode is in the form of a tube havingan axial lumen extending therethrough.
 4. A medical probe device as inclaim 1 wherein said conductive electrode is in the form of a solid wirehaving a sharp end.
 5. A medical probe device as in claim 1 wherein saidprobe end of said catheter is formed with a port.
 6. A medical probedevice as in claim 5 wherein said probe end is formed with two spacedapart ports extending in a plane perpendicular to the longitudinal axisof the probe end.
 7. A medical probe device as in claim 1 together withultrasound means at the distal end of the stylet assembly for providingan electrical signal for indicating the position of the distal extremityof the stylet assembly in the body.
 8. A medical probe device as inclaim 1 including temperature sensor means mounted on the distalextremity of the stylet assembly for sensing temperature.
 9. A medicalprobe device as in claim 1 wherein the conductive electrode is formed ofa highly flexible metal.
 10. A medical probe device as in claim 9wherein the highly flexible metal is a nickel-titanium alloy.
 11. Amedical probe device as in claim 1 wherein said probe end has a curvedpathway formed therein leading from the passageway to a port facing in adirection substantially perpendicular to the longitudinal axis.
 12. Amedical probe device as in claim 11 wherein the curved pathway has aradius that permits slidable deployment of the distal extremity of thestylet assembly through the pathway and through the port.
 13. A medicalprobe device as in claim 12 wherein said pathway has a radius of 0.5 cmor less.
 14. A medical probe device as in claim 1 together with at leastone grounding plate adapted to be placed in contact with the human maleand spaced from the prostate, the grounding plate being adapted toreceive radio frequency energy passing from the conductive electrodethrough the tissue of the prostate to be ablated.
 15. A medical probedevice as in claim 1 wherein the sleeve of insulating material has adistal extremity which is tapered inwardly and distally.
 16. A medicalprobe device as in claim 1 wherein said sleeve of insulating materialhas a lumen therein, said lumen in said sleeve of insulating materialhaving a diameter, said conductive electrode having a diameter which isless than the diameter of the lumen, said conductive electrode having adistal extremity with a sharp blade tip formed thereon having a lateraldimension greater than the diameter of the lumen in the sleeve to form ashoulder to prevent retraction of the sharp blade tip into the lumen ofthe sleeve.
 17. A medical probe device as in claim 16 wherein the sharpblade tip is provided with first and second sidewise extending cuttingedges forming a vee with the vee having an apex extending distally. 18.A medical probe device as in claim 1 wherein the probe end of thecatheter is more flexible than the control end of the catheter.
 19. Amedical probe device as in claim 1 comprising a control handle adaptedto be grasped by the human hand attached to the control end of thecatheter and forming a portion of the control means wherein said controlmeans is accessible from the control handle.
 20. A medical probe deviceas in claim 19 wherein said control means comprises slidable membersslidably mounted on the handle and secured to the stylet assembly, theslidable members being adapted to be engaged by the fingers of the handholding the control handle.
 21. A medical probe device as in claim 19comprising a control handle attached to the control end of the catheterwherein said control means includes a first slidable member slidablymounted on the control handle and connected to said sleeve of insulatingmaterial and a second slidable member slidably mounted on the controlhandle and connected to the conductive electrode.
 22. A medical probedevice as in claim 21 wherein the first and second slidable members aremounted on the control handle for both separate and/or coordinatedmovement thereon.
 23. A medical probe device as in claim 22 wherein thecontrol handle has a top wall with first and second spaced apartparallel longitudinally extending slots formed therein, said first andsecond slidable members being slidably mounted in the first and secondslots, each of said first and second members including a finger engagingsurface extending above the top wall.
 24. A medical probe for thetreatment of benign prostatic hypertrophy by radio frequency ablation ofa target volume in tissue of a prostate of a human male having a bladderwith a base and a penis with a urethra therein formed by a urethral wallextending into the base of the bladder along a longitudinal axis withthe tissue of the prostate surrounding the urethra near the base of thebladder comprising an elongate member having proximal and distalextremities and having a longitudinal axis and being sized to be able toenter the urethra and having a length so that when the distal extremityis disposed in the vicinity of the prostate the proximal extremity isoutside of the urethra, said elongate member having a sidewall with apassageway therein extending along the longitudinal axis, said distalextremity having a port in communication with the passageway, a radiofrequency electrode of an electrically conductive material disposed insaid passageway and having a sharpened tip, a sleeve formed ofinsulating material coaxially and slidably mounted on said radiofrequency electrode and disposed in said passageway, a handle secured tothe proximal extremity of the elongate member and means carried by thehandle and connected to said radio frequency electrode and to saidsleeve for causing relative sliding movement of said radio frequencyelectrode and said sleeve whereby a preselected length of the radiofrequency electrode is exposed in the target volume when the radiofrequency electrode has been advanced into the target volume with thesleeve of insulating material extending through the urethral wall sothat tissue of the prostate in the target volume surrounds thepreselected length of the radio frequency electrode and the tissue ofthe prostate can be ablated while protecting the urethral wall fromablation.
 25. A medical probe as in claim 24 wherein the means carriedby the handle and connected to the radio frequency electrode and to saidsleeve is movable to cause the sleeve to extend over the radio frequencyelectrode to provide additional rigidity to the radio frequencyelectrode whereby the radio frequency electrode in combination with thesleeve are used to puncture and penetrate the urethral wall and toadvance into the target volume of the tissue of the prostate beyond theurethral wall and thereafter said radio frequency electrode and saidsleeve are movable relative to each other so that a preselected lengthof the radio frequency electrode can be exposed within the target volumewhereby when radio frequency energy is supplied to the radio frequencyelectrode the tissue of the prostate surrounding the radio frequencyelectrode is heated to cause ablation of the tissue in the target volumewhile the sleeve protects the urethral wall from the radio frequencyenergy to prevent damage to the same during the time that the radiofrequency energy is heating the tissue of the prostate.
 26. A medicalprobe device for radio frequency medical treatment of target tissue of aprostate through a urethra formed by a urethral wall extending throughthe prostate comprising a catheter having a proximal extremity and adistal extremity and having a stylet guide housing at the distalextremity, a stylet slidably mounted in the housing and having a distalextremity movable between a retracted position within the housing and anextended position outside the housing, said stylet having a flexibleradio frequency conductive electrode with a sharpened tip and aninsulating sleeve surrounding the electrode and movable relative to theelectrode, handle means carried by the proximal extremity of thecatheter for introducing the catheter through the urethra to a regionadjacent to the prostate, means carried by the handle means andconnected to the stylet for advancing the stylet from the catheter tothe extended position through the wall of the urethra into the prostateso that the sharpened tip of the electrode punctures and penetrates theurethral wall with the sleeve extending through the urethral wall andmeans carried by the handle means for causing relative movement betweenthe electrode and the insulating sleeve to expose a predetermined lengthof the electrode in the target tissue of the prostate with theinsulating sleeve extending through the urethral wall whereby whensufficient radio frequency energy is supplied to the electrode thetemperature of the target tissue of the prostate adjacent thepredetermined length of electrode is raised to a temperature to causedestruction of cells of the target tissue of the prostate while theurethral wall is protected from the radio frequency energy supplied tothe electrode.
 27. A medical probe device as in claim 26 together with atemperature sensor mounted on the stylet guide housing for indicatingthe temperature of the tissue adjacent to the guide housing.
 28. Amedical probe as in claim 26 together with an additional stylet assemblyslidably mounted in the housing and having a distal extremity movablebetween a retracted position within the housing and an extended positionoutside the housing, said additional stylet assembly having a flexibleradio frequency conductive electrode with a sharpened tip and aninsulating sleeve surrounding the electrode and movable relative to theelectrode.
 29. A medical probe device for treatment of a prostate of ahuman male having a bladder with a base with a urethra formed by aurethral wall extending into the base of the bladder with the prostatehaving tissue surrounding the urethra near the base of the bladdercomprising an elongate member having proximal and distal extremities anda passageway extending from the proximal extremity to the distalextremity along a longitudinal axis, a flexible stylet assembly slidablymounted in the passageway in the elongate member and having a flexibledistal extremity, said stylet assembly including a conductive electrodeand a sleeve of insulating material surrounding the conductive electrodeand permitting a predetermined portion of the conductive electrode to beexposed, control means secured to the stylet assembly for causingmovement of the distal extremity of the stylet assembly between aretracted position disposed within the passageway and an extendedposition disposed outwardly in a direction away from the longitudinalaxis whereby the stylet assembly can extend through the urethral wallinto the tissue of the prostate with the conductive electrode beingexposed in the tissue of the prostate and means coupled to the controlmeans and to the conductive electrode for supplying radio frequencyenergy to the conductive electrode for causing ablation of tissue in theprostate.
 30. A device as in claim 29 wherein the conductive electrodeis in the form of a tube having an axial lumen extending therethrough.31. A device as in claim 29 together with ultrasound means carried bythe distal extremity of the elongate member for providing an electricalsignal for indicating the position of the device in the human male. 32.A device as in claim 31 wherein said ultrasound means is mounted on theinsulating sleeve.
 33. A device as in claim 29 together with temperaturesensing means mounted on the insulating sleeve.
 34. A medical device fortreatment of a prostate of a human male having a bladder with a basewith a urethra formed by a urethral wall extending into the base of thebladder with the prostate having tissue surrounding the urethra near thebase of the bladder comprising an elongate member having proximal anddistal extremities and a passageway extending from the proximalextremity to the distal extremity along a longitudinal axis, first andsecond stylet assemblies slidably mounted in the passageway in theelongate member and each having a flexible distal extremity, each ofsaid stylet assemblies comprising a conductive electrode and a sleeve ofinsulating material surrounding the conductive electrode and permittinga predetermined portion of the conductive electrode to be exposed,control means secured to the first and second stylet assemblies forcausing movement of the distal extremities of the stylet assembliesbetween retracted positions disposed within the passageway and extendedpositions disposed outwardly in a direction which is at an angle withrespect to the longitudinal axis so that when the elongate member isdisposed in the urethra with the distal extremity in proximity to theprostate the stylet assemblies extend through the urethral wall into thetissue of the prostate with the conductive electrodes being exposed inthe tissue of the prostate and means coupled to the control means and tothe conductive electrodes for supplying radio frequency energy to theconductive electrodes for causing ablation of tissue in the prostate.35. A device as in claim 34 wherein said control means includes meansfor moving both of said first and second stylet assembliessimultaneously.
 36. A device as in claim 34 together with means carriedby the elongate member for measuring the temperature at the distalextremity of the elongate member.
 37. A device as in claim 36 whereinsaid means for measuring temperature is mounted on at least one of theinsulating sleeves.
 38. A device as in claim 34 together with meanscarried by the elongate member for measuring impedance of tissue in theprostate.